Magnetic resonance imaging switching power amplifier system and methods

Abstract

This disclosure regards a magnetic resonance imaging system including a scanner, and gradient drivers. The scanner is to be implemented within a scan room that is shielded from electromagnetic interference. Gradient coils are designed to create a linear gradient in the magnetic field generated in the scanner by a primary magnet. These coils are energized by gradient drivers. The gradient drivers use transformers and other electrical devices in a switching stage configured to generate pulse-width-modulated power. The transformers may have non-magnetic cores to facilitate implementing the gradient drivers within the scan room. The gradient drivers also use a filtering stage which uses inductors and other electrical devices to smooth the pulse-width-modulated power. The inductors within the filters may have non-magnetic cores to facilitate implementing the gradient driver within the scan room. Additionally, an inductor with a hollow wire may be used to circulate fluid to facilitate cooling the gradient driver.

The invention claimed is: 
     
       1. A switching power amplifier to be implemented in a scan room along with a scanner of a magnetic resonance image system, comprising:
 a switching stage configured to generate pulse-width-modulated electrical power based at least in part on electrical power received from a power source; and a filtering stage electrically coupled to the switching stage, wherein: 
 the filtering stage comprises a first inductor formed from hollow tubing, wherein the first inductor comprises a first air core to facilitate implementing the switching power amplifier in the scan room; and 
 the filtering stage is configured to generate smoothed electrical power based at least in part on the pulse-width-modulated electrical power generated by the switching stage using electrical energy stored in the first inductor; and a transformer comprising a second air core electrically coupled between the switching stage and the filtering stage to facilitate supplying the pulse-width-modulated electrical power from the switching stage to the filtering stage, wherein the transformer comprises the second air core to facilitate implementing the switching power amplifier in the scan room 
 
       wherein the switching power amplifier is configured to be electrically coupled to the power source via a first cable bundle, wherein the first cable bundle comprises:
 a first cable and a second cable configured to be electrically coupled between the switching power amplifier and the power source, wherein: a first length of the first cable is expected to be located within the scan room; and 
 a second length of the second cable is expected to be located within the scan room; 
 a first cable shield formed around the first cable at least along the first length; 
 a second cable shield formed around the second cable at least along the second length; and 
 a first bundle shield around the first cable, the second cable, the first cable shield, and the second cable shield. 
 
     
     
       2. The switching power amplifier of  claim 1 , wherein the first inductor is configured to be fluidly coupled to a cooling system of the magnetic resonance imaging system to facilitate cooling the magnetic resonance imaging system by enabling the cooling system to circulate cooling fluid through the hollow tubing used to form the first inductor. 
     
     
       3. The switching power amplifier of  claim 1 , wherein:
 the filtering stage comprises:
 a second inductor electrically coupled on a first side of the first inductor; and 
 a third inductor electrically coupled on a second side of the first inductor; and 
 
 the first inductor is physically coupled between the first inductor and second inductor to facilitate heat transfer with cooling fluid circulated through a hollow interior of the first inductor. 
 
     
     
       4. The switching power amplifier of  claim 3 , wherein:
 the second inductor comprises a third air core to facilitate implementing the switching power amplifier in the scan room; and 
 the third inductor comprises a fourth air core to facilitate implementing the switching power amplifier in the scan room. 
 
     
     
       5. The switching power amplifier of  claim 1 , wherein the switching power amplifier is configured to be electrically coupled to a gradient coil in the scanner via a second cable bundle, wherein the second cable bundle comprises:
 a third cable and a fourth cable configured to be electrically coupled between the switching power amplifier and the gradient coil; 
 a third cable shield formed around the third cable along its entire length; 
 a fourth cable shield formed around the fourth cable along its entire length; and 
 a second bundle shield around the third cable, the fourth cable, the third cable shield, and the fourth cable shield. 
 
     
     
       6. A switching power amplifier to be implemented in a scan room along with a scanner of a magnetic resonance image system, comprising:
 a switching stage configured to generate pulse-width-modulated electrical power based at least in part on electrical power received from a power source; 
 a filtering stage electrically coupled to the switching stage, wherein: 
 the filtering stage comprises a first inductor formed from hollow tubing, wherein the first inductor comprises a first non-magnetic core to facilitate implementing the switching power amplifier in the scan room; and 
 the filtering stage is configured to generate smoothed electrical power based at least in part on the pulse-width-modulated electrical power generated by the switching stage using electrical energy stored in the first inductor; and a transformer comprising a second non-magnetic core electrically coupled between the switching stage and the filtering stage to facilitate supplying the pulse-width-modulated electrical power from the switching stage to the filtering stage, wherein the transformer comprises the second non-magnetic core to facilitate implementing the switching power amplifier in the scan room 
 
       wherein the switching power amplifier is configured to be electrically coupled to the power source via a first cable bundle, wherein the first cable bundle comprises;
 a first cable and a second cable configured to be electrically coupled between the switching power amplifier and the power source, wherein: 
 a first length of the first cable is expected to be located within the scan room; and 
 a second length of the second cable is expected to be located within the scan room; 
 a first cable shield formed around the first cable at least along the first length; a second cable shield formed around the second cable at least along the second length; and 
 a first bundle shield around the first cable, the second cable, the first cable shield, and the second cable shield. 
 
     
     
       7. The switching power amplifier of  claim 6 , wherein the first inductor is configured to be fluidly coupled to a cooling system of the magnetic resonance imaging system to facilitate cooling the magnetic resonance imaging system by enabling the cooling system to circulate cooling fluid through the hollow tubing used to form the first inductor. 
     
     
       8. The switching power amplifier of  claim 6 , wherein:
 the filtering stage comprises:
 a second inductor electrically coupled on a first side of the first inductor; and 
 a third inductor electrically coupled on a second side of the first inductor; and 
 
 the first inductor is physically coupled between the first inductor and second inductor to facilitate heat transfer with cooling fluid circulated through a hollow interior of the first inductor. 
 
     
     
       9. The switching power amplifier of  claim 8 , wherein:
 the second inductor comprises a third non-magnetic core to facilitate implementing the switching power amplifier in the scan room; and 
 the third inductor comprises a fourth non-magnetic core to facilitate implementing the switching power amplifier in the scan room. 
 
     
     
       10. The switching power amplifier of  claim 6 , wherein the switching power amplifier is configured to be electrically coupled to a gradient coil in the scanner via a second cable bundle, wherein the second cable bundle comprises:
 a third cable and a fourth cable configured to be electrically coupled between the switching power amplifier and the gradient coil; 
 a third cable shield formed around the third cable along its entire length; a fourth cable shield formed around the fourth cable along its entire length; and a second bundle shield around the third cable, the fourth cable, the third cable shield, and the fourth cable shield. 
 
     
     
       11. The switching power amplifier of  claim 10 , wherein the transformer is implemented in a gradient driver of the magnetic resonance image system, wherein:
 the first cable shield is electrically coupled to the gradient driver in the scan room along with the scanner of the magnetic resonance image system; 
 the second cable shield is electrically coupled to the gradient driver in the scan room along with the scanner of the magnetic resonance image system; and 
 the first cable and the second cable are electrically coupled between the gradient driver and the gradient coil. 
 
     
     
       12. The switching power amplifier of  claim 11 , wherein:
 the third cable shield is electrically coupled to the gradient driver in the scan room along with the scanner of the magnetic resonance image system; and 
 the fourth cable shield is electrically coupled to the gradient driver in the scan room along with the scanner of the magnetic resonance image system. 
 
     
     
       13. A method for implementing a magnetic resonance imaging system, comprising: electrically coupling a first transformer implemented with a first non-magnetic core in
 a first gradient driver of the magnetic resonance imaging system between a first switching stage and a first filtering stage to facilitate supplying first pulse-width-modulated electrical power generated by the first switching stage to the first filtering stage;
 implementing a first inductor with a second non-magnetic core and a first hollow interior that enables fluid flow through the first inductor; and 
 electrically coupling the first inductor in the first filtering stage of the first gradient driver to facilitate smoothing the first pulse-width-modulated electrical power and supplying first smoothed electrical power to a first gradient coil electrically coupled to the first gradient driver 
 forming a first cable shield around a first cable expected to be electrically coupled to the first gradient driver in a scan room along with a scanner of the magnetic resonance imaging system; 
 forming a second cable shield around a second cable expected to be electrically coupled to the first gradient driver in the scan room along with the scanner; and 
 forming a first bundle shield around a first cable bundle comprising the first cable, the first cable shield, the second cable, and the second cable shield. 
 
 
     
     
       14. The method of  claim 13 , comprising fluidly coupling the first inductor with a cooling system of the magnetic resonance imaging system to facilitate cooling the magnetic resonance imaging system by enabling the cooling system to circulate cooling fluid through the first hollow interior of the first inductor. 
     
     
       15. The method of  claim 13 , comprising:
 forming a third cable shield around a third cable expected to be electrically coupled to the first gradient driver in the scan room along with the scanner; 
 forming a fourth cable shield around a fourth cable expected to be electrically coupled to the first gradient driver in the scan room along with the scanner; 
 forming a second bundle shield around a second cable bundle comprising the third cable, the third cable shield, the fourth cable, and the fourth cable shield; electrically coupling the third cable and the fourth cable between the first gradient driver and a power source external from the scan room; and 
 electrically coupling the first cable and the second cable between the first gradient driver and the first gradient coil. 
 
     
     
       16. The method of  claim 13 , wherein implementing the first inductor comprises coiling an electrically conductive cooling tube around an air core. 
     
     
       17. The method of  claim 13 , comprising:
 electrically coupling a second transformer implemented with a third non-magnetic core in a second gradient driver of the magnetic resonance imaging system between a second switching stage and a second filtering stage to facilitate supplying second pulse-width-modulated electrical power generated by the second switching stage to the second filtering stage; 
 implementing a second inductor with a fourth non-magnetic core and a second hollow interior that enables fluid flow through the second inductor; and 
 electrically coupling the second inductor in the second filtering stage of the second gradient driver to facilitate smoothing the second pulse-width-modulated electrical power and supplying second smoothed electrical power to a second gradient coil electrically coupled to the second gradient driver.